1. Field of the Invention
This invention pertains to evanescent spectroscopic analysis of biomedical samples, particularly flesh and organs, using chalcogenide glass fibers.
2. Description of Related Art
There is significant interest in the medical community for non-invasive and minimal-invasive medical diagnostic techniques using fiber optics. Silica based fibers have been used in biomedical applications for a considerable time for performing laser surgery, visible examination by endoscope and such, as well as sensing and analysis using biochemical compounds such as enzymes and antibodies. Since silica fibers transmit between the near ultraviolet and about 2 microns, the analysis is limited. For example, many biomedical samples have important identifying indicia beyond about 2 microns. Wavelengths at about 3 microns or 6.4 microns, correspond to the OH stretching absorption and the Amide II (N-H stretching vibration) absorption in proteins, respectively. This problem of insufficient transmission is further compounded by the fact that 6.45 micron wavelength is absorbed by the atmosphere and precautions must be taken to minimize atmospheric absorption over long path lengths. In the case of cancerous tumors or unidentified foreign inclusions, it has been the practice that the appropriate section was usually removed from the body, sliced into a thin section, desiccated and then characterized using optical microscopy. More recently, thin sections have been characterized using infrared spectroscopy whereby cancer cells have exhibited unique and characteristic special features in the 2-12 micron wavelength region. The chalcogenide glass fibers transmit in the 2-12 micron wavelength region which coincides with the wavelength region of importance in biomedical spectroscopy. Therefore, chalcogenide fibers can be used for infrared spectroscopy. Furthermore, these fibers should be well suited for non-invasive spectroscopy and identification by enhancing spectroscopic analysis of human and animal flesh, tissue and human organs.
The articles entitled "Diagnostics of cancer by fiberoptic evanescent wave FTIR (FEW-FTIR) spectroscopy" by Afanasyeva et al published in 1996 in vol. 2928 of SPIE; "Detection of spectral differences between normal and cancerous oral tissue using near-infrared spectroscopy" by Cooney et al believed to be published in 1998 in Btu A 2-1/67; "MIR - fiber spectroscopy for minimal invasive diagnostics" by Artjushenko et al published in 1995 in vol. 2631 of SPIE; and "Infrared fibers: power delivery and medical applications" by Artjushenko et al published in 1995 in vol. 2396 of SPIE, are pertinent hereto and relate generally to evanescent spectroscopy and to detection of cancerous tissues.